Purpose: Monocytes are blood circulating innate immune cells that can recognize microbial components and modulate the consequent innate and adaptive immune responses through the release of pro-inflammatory and anti-inflammatory cytokines. So far, the effect of the facultative parasite Acanthamoeba on monocyte activation is poorly investigated. Therefore, the purpose of this study was to evaluate the kinetics and pattern of pro-inflammatory and anti-inflammatory cytokines released by human monocytes in response to Acanthamoeba. Methods: The human monocytic cell line THP-1 and primary human peripheral blood monocytes (PBMCs) were either co-incubated with whole and living trophozoites of a clinical isolate of Acanthamoeba castellanii or stimulated with amoeba derived cell free conditioned medium (aCM), in vitro. Release of TNF-α, IL-6, IL-12 and IL-10 was investigated at specific hours post-stimulation, by Enzyme Linked Immuno Sorbent Assay (ELISA). Results: Herein, we showed that both A. castellanii trophozoites and aCM induced an early release of IL-10 by monocytes, significant since the earliest time point (1.3 h). aCM was showed to be more effective in stimulating all pro-inflammatory cytokines investigated, in both cellular models used. On the other hand, trophozoites induced the production of TNF-α by both THP-1 and PBMCs; whereas IL-6 and IL-12 were only slightly detected in PBMCs and THP-1 respectively. Discussion: For the first time, it is demonstrated that Acanthamoeba, in particular amoebic soluble molecules, can induce an early production of IL-10 as well as TNF-α, IL-6 and IL-12 by human monocytes. This early coexistence of both pro-inflammatory and anti-inflammatory cytokine might influence the infection outcome, promoting inappropriate immune responses as well as immune evasion of Acanthamoeba. Conclusions: Monocyte/Acanthamoeba interaction leads to a peculiar cytokine pattern, that might influence the establishment and the nature of the infection. This work was supported by grant CPR.59632, LR72012MATTANA from the Regione Sardegna.
Acanthamoeba castellanii induces coexisting and opposed immune responses in human monocytes / Antonella, Cano; Manuela, Sanna; Juliano, Claudia Clelia Assunta; Mattana, Antonella. - (2016), pp. 39-39. (Intervento presentato al convegno International Summer Course "INTRINSIC AND INNATE IMMUNITY TO PATHOGENS", tenutosi a Novarello Congress Center, Novara (Italy) nel 23-25 June 2016).